fairer sort is that
which is made up of equal and similar parts and is transparent; that
which has the opposite qualities is inferior. But when all the watery
part is suddenly drawn out by fire, a more brittle substance is formed,
to which we give the name of pottery. Sometimes also moisture may
remain, and the earth which has been fused by fire becomes, when cool,
a certain stone of a black colour. A like separation of the water
which had been copiously mingled with them may occur in two substances
composed of finer particles of earth and of a briny nature; out of
either of them a half-solid-body is then formed, soluble in water--the
one, soda, which is used for purging away oil and earth, the other,
salt, which harmonizes so well in combinations pleasing to the palate,
and is, as the law testifies, a substance dear to the gods. The
compounds of earth and water are not soluble by water, but by fire only,
and for this reason:--Neither fire nor air melt masses of earth; for
their particles, being smaller than the interstices in its structure,
have plenty of room to move without forcing their way, and so they leave
the earth unmelted and undissolved; but particles of water, which are
larger, force a passage, and dissolve and melt the earth. Wherefore
earth when not consolidated by force is dissolved by water only; when
consolidated, by nothing but fire; for this is the only body which can
find an entrance. The cohesion of water again, when very strong, is
dissolved by fire only--when weaker, then either by air or fire--the
former entering the interstices, and the latter penetrating even the
triangles. But nothing can dissolve air, when strongly condensed, which
does not reach the elements or triangles; or if not strongly condensed,
then only fire can dissolve it. As to bodies composed of earth and
water, while the water occupies the vacant interstices of the earth
in them which are compressed by force, the particles of water which
approach them from without, finding no entrance, flow around the entire
mass and leave it undissolved; but the particles of fire, entering into
the interstices of the water, do to the water what water does to earth
and fire to air (The text seems to be corrupt.), and are the sole causes
of the compound body of earth and water liquefying and becoming fluid.
Now these bodies are of two kinds; some of them, such as glass and the
fusible sort of stones, have less water than they have earth; on the
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